package singleton.test;

/**
 * @author shkstart
 * @date 2022/5/16 - 22:01
 */
// * 单例模式的懒汉式实现
public class SingletonTest2 {
    public static void main(String[] args) {
        Order order = Order.getInstance();
        Order order1 = Order.getInstance();
        System.out.println(order == order1);//true
    }

}

class Order {
    //1.私有化类的构造器
    private Order() {

    }

    //2.声明当前类对象，没有初始化
    //4.此对象也必须声明为static的
    private static Order instance = null;


    //3.声明public、static的返回当前类对象的方法
    public static Order getInstance() {
//        此时的懒汉式,是不安全的
        if (instance == null) {
            instance = new Order();
        }

        return instance;
    }
}
